﻿GEOLOGY 
  OF 
  MADAGASCAK. 
  323 
  

  

  toby 
  on 
  the 
  north-west 
  coast. 
  But 
  these 
  reports 
  I 
  have 
  had 
  no 
  

   opportunity 
  of 
  verifying. 
  Dr. 
  G. 
  W. 
  Parker 
  finds 
  that 
  an 
  examina- 
  

   tion 
  of 
  the 
  water 
  from 
  springs 
  in 
  the 
  district 
  of 
  Antsirabe 
  gives 
  the 
  

   following 
  results 
  : 
  — 
  

  

  " 
  On 
  evaporation, 
  one 
  pint 
  (20 
  oz.) 
  of 
  water 
  from 
  each 
  spring 
  

   yielded 
  the 
  following 
  quantities 
  of 
  solid 
  salts 
  : 
  — 
  

  

  Spring 
  No. 
  1 
  yielded 
  40 
  grains 
  of 
  salts, 
  or 
  2*0 
  grains 
  to 
  1 
  oz. 
  of 
  water. 
  

  

  55 
  55 
  ^ 
  55 
  ^^ 
  55 
  55 
  55 
  -*-'«' 
  55 
  ■*■ 
  55 
  55 
  

  

  3 
  42 
  2-1 
  1 
  

  

  55 
  55 
  w 
  55 
  ^^ 
  55 
  55 
  55 
  "^ 
  x 
  55 
  ■*- 
  55 
  55 
  

  

  4 
  28 
  1-4 
  1 
  

  

  55 
  55 
  ^ 
  55 
  ^ 
  u 
  55 
  55 
  55 
  ■*- 
  ^ 
  55 
  L 
  55 
  55 
  

  

  All 
  these 
  springs 
  contain 
  the 
  same 
  ingredients, 
  viz. 
  lime, 
  magnesia, 
  

   soda, 
  and 
  potash, 
  in 
  combination 
  with 
  chlorine, 
  iodine, 
  sulphuric 
  

   acid, 
  and 
  carbonic 
  acid, 
  with 
  the 
  addition 
  of 
  free 
  carbonic 
  acid 
  gas." 
  

  

  At 
  Antsirabe 
  there 
  is 
  a 
  deposit 
  from 
  one 
  of 
  these 
  springs 
  of 
  car- 
  

   bonate 
  of 
  lime, 
  which 
  is 
  occasionally 
  used 
  for 
  building 
  purposes 
  in 
  

   the 
  capital. 
  Bubbles 
  of 
  carbonic 
  acid 
  may 
  be 
  seen 
  rising 
  from 
  the 
  

   surface 
  of 
  the 
  deposit, 
  and 
  at 
  one 
  point, 
  where 
  there 
  is 
  a 
  small 
  

   spring, 
  a 
  mass 
  of 
  calc-sinter 
  has 
  been 
  formed 
  which 
  is 
  80 
  feet 
  long 
  

   by 
  15 
  feet 
  high. 
  But 
  the 
  deposit 
  also 
  exists 
  in 
  several 
  of 
  the 
  

   valleys 
  in 
  the 
  vicinity 
  to 
  an 
  unknown 
  depth. 
  In 
  one 
  of 
  the 
  

   small 
  valleys, 
  where 
  there 
  is 
  a 
  discharge 
  of 
  carbonic 
  acid 
  gas, 
  there 
  

   may 
  be 
  seen 
  the 
  dead 
  bodies 
  of 
  grasshoppers, 
  &c, 
  that 
  had 
  ventured 
  

   too 
  near 
  the 
  noxious 
  element. 
  

  

  In 
  one 
  of 
  the 
  valleys 
  in 
  the 
  vicinity 
  of 
  the 
  crater-rings 
  of 
  Ambo- 
  

   hidratrimo, 
  spoken 
  of 
  above, 
  there 
  is 
  a 
  deposit 
  of 
  siliceous 
  sinter. 
  

   It 
  appears 
  in 
  one 
  or 
  two 
  places, 
  scarcely 
  rising 
  above 
  the 
  surface 
  of 
  

   the 
  ground, 
  in 
  a 
  valley 
  of 
  rice-fields, 
  and 
  has 
  been 
  deposited 
  by 
  

   springs 
  which 
  have 
  long 
  since 
  ceased 
  to 
  flow. 
  The 
  sinter 
  is 
  exceed- 
  

   ingly 
  hard 
  and 
  compact, 
  and 
  is 
  used 
  by 
  the 
  natives 
  for 
  fire-flints. 
  

   They 
  know 
  it 
  as 
  vatofangala. 
  In 
  some 
  portions 
  of 
  it 
  numerous 
  

   fossils 
  of 
  what 
  appear 
  to 
  be 
  a 
  species 
  of 
  Equisetum 
  are 
  imbedded. 
  

  

  About 
  twenty 
  or 
  thirty 
  miles 
  to 
  the 
  north 
  of 
  Ambatobe, 
  in 
  North 
  

   Antsihanaka, 
  at 
  a 
  place 
  named 
  Analaroamaso, 
  there 
  is 
  a 
  consider- 
  

   able 
  deposit 
  of 
  siliceous 
  sinter, 
  which 
  contains 
  particles 
  of 
  sand 
  

   and 
  pebbles 
  imbedded 
  in 
  it. 
  Ten 
  or 
  twelve 
  miles 
  further 
  north, 
  

   again, 
  there 
  is 
  a 
  second 
  deposit 
  of 
  a 
  similar 
  character. 
  Here 
  there 
  

   is 
  also 
  a 
  circular 
  shallow 
  basin 
  seventy 
  or 
  eighty 
  feet 
  in 
  diameter, 
  

   with 
  a 
  ledge 
  of 
  sinter 
  round 
  it. 
  This 
  is 
  probably 
  the 
  site 
  of 
  an 
  

   extinct 
  geyser. 
  These 
  sinter 
  -deposits 
  are 
  in 
  the 
  bed 
  of 
  the 
  ancient 
  

   lake 
  described 
  above, 
  and, 
  with 
  the 
  miniature 
  craters 
  that 
  occur 
  

   here 
  and 
  there, 
  are 
  proofs 
  of 
  recent 
  volcanic 
  activity. 
  There 
  is 
  

   also 
  a 
  small 
  deposit 
  of 
  siliceous 
  sinter 
  a 
  little 
  to 
  the 
  east 
  of 
  Andra- 
  

   nomafana 
  (between 
  the 
  capital 
  and 
  the 
  east 
  coast), 
  where 
  also 
  there 
  

   is 
  much 
  basalt. 
  

  

  Eaethquakes. 
  

  

  So 
  little 
  is 
  known 
  respecting 
  earthquake-phenomena 
  in 
  Madagascar, 
  

   no 
  scientific 
  observations 
  ever 
  having 
  been 
  instituted, 
  that 
  it 
  is 
  

   scarcely 
  worth 
  while 
  to 
  refer 
  to 
  the 
  subject. 
  However, 
  it 
  may 
  be 
  

  

  